Generally, a balance shaft module of a vehicle is installed in a lower part of a cylinder block of an engine in order to reduce vibration and noise of the engine. For example, as shown in FIG. 1, two balance shaft 2 are rotatably installed in a balance shaft housing 1, a gear or a sprocket 3 is formed at a front end of one balance shaft 2 to receive rotating power of the engine, and a plurality of oil discharge holes 1a are formed side by side in a lower part of balance shaft housing 1.
Further, a part of engine oil 5 held in an oil pan flows in balance shaft housing 1 as shown by a cross-section in FIG. 2 and engine oil 5 is suitably discharged outside of the balance shaft module through oil discharge holes 1a formed in an upper part of the balance shaft housing when balance shaft 2 rotates as shown by an arrow.
In the structure of the known balance shaft module, since oil discharge holes 1a are formed in an upright direction when the engine oil is discharged through the oil discharge holes by the balance shaft, the oil pumped by the balance shaft is discharged outside of the balance shaft module through the oil discharge holes and reflows in the balance shaft module through the oil discharge holes.
To address the above, as shown in FIG. 3, an oil guide 6 may be suitably installed so that the engine oil discharged through center oil discharge hole 1a is smoothly guided outside of the balance shaft module. The oil guide 6 interferes with a ladder frame 4 that is mounted on the upper part of the balance shaft module to suitably reduce the vibration and noise of the engine. In general, the oil guide 6 is not easy to install and the size of the balance shaft module increases.
The above information disclosed in this the Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.